中亚热带丘陵红壤区森林演替典型阶段土壤氮磷有效性

在中亚热带典型丘陵红壤区选取裸露地、马尾松(Pinus massoniana)林地、针阔混交林地、常绿阔叶林地为研究对象,开展土壤氮(N)、磷(P)供应、有效性及其耦合过程的研究.结果表明,土壤有机C、全N、净矿化速率、中性磷酸酶活性表现为随森林演替进展呈现逐步提高的变化趋势;而土壤全P、C/N、C/P、氨化速率、硝化速率、树脂P、NaHCO3-P、NaOH-P、声波P、酸性P、总有效P、酸性磷酸酶活性未表现出此趋势;但反映N、P有效供应的指标,除氨化速率、树脂P和酸性磷酸酶外,在常绿阔叶林中均为最高.相关分析表明大部分N、P供应指标之间存在显著相关性(P<0.05).丘陵红壤区森林演替初级阶段P的限制性明显强于N,土壤N、P供应在森林演替进展过程中可以逐步得到优化而实现协调供应.以常绿阔叶林为中亚热带丘陵红壤区植被恢复的最终目标是可行和理想的.     

Uncertainty in life cycle impact assessment of toxic releases practical experiences - arguments for a reductionalistic approach?

This paper describes the experience with impact assessment of toxic releases in a Substance Flow Analysis (SFA) for PVC in Sweden. For this system, all emissions related to the PVC-chain were inventoried. They have been evaluated making use of the Life Cycle Impact Assessment (LCIA) step from the CMI.-guide, including the new toxicity equivalency factors calculated with the Uniform System for Evaluation of Substances (USES). The application of this method led to the conclusion that I.CA Impact Assessment of toxic releases is still a major bottleneck: the USES-equivalency factors are not to he trusted due to outdated data, inappropriate defaults, etc. in the USES’ substance properties database. Therefore, a second USES-ser of factors was calculated that differed up to factors of 1,000 or more from the old ones. Even these factors probably suffer from unacceptable high structural, in practice not reducible uncertainties. In conclusion, we warn the LCA community not to overestimate the possibility of LCA Impact Assessment to obtain a meaningfull priority setting with regard to toxicity problems. Instead, we propose developing indicator systems for LCIA of toxic releases that genuinely deal with all relevant types of uncertainty: data uncertainty, modelling uncertainty and particularly paradigmatic uncertainty.     

Use of monoclonal and polyclonal antibodies as structural and topographical probes for hepatic epoxide hydrolase

Monoclonal antibodies have been prepared against rat liver epoxide hydrolase (EH), some of which gave precipitation lines on immunodiffusion against pure EH suggesting the presence of repetitive structural domains on the enzyme. Using ELISA, with polyclonal antibodies to rat and rabbit liver EH, reactivity and therefore structural similarities between EH of all species tested, including human, were observed. This was in contrast to immunodiffusion results demonstrating the limitations of the latter technique. Using monoclonal antibodies in ELISA, greatest structural similarity was between rat, mouse, and Syrian hamster EH and relatively little between rat and human. Two of the antibodies reacted with nearly all species tested and may be directed towards critical sites on the enzyme. This and most of the EH molecule would appear to be localised on the cytoplasmic surface of the endoplasmic reticulum.     

Epifaunal colonization of the Loch Linnhe artificial reef: Influence of substratum on epifaunal assemblage structure

A one-year study was carried out off the west coast of Scotland to compare the epifaunal colonization of concrete material used in the construction of the Loch Linnhe artificial reef with that on four other types of artificial substrata (preservative treated wood, rubber, steel and PVC). Settlement panels made from each of the materials were submerged in a vertical orientation during four seasonal exposure periods. There were clear seasonal trends across the four exposure periods with higher epifaunal biodiversity on all types of panel in the spring and summer exposure periods. Epifaunal assemblage structure was significantly different between the five types of material after each three-month exposure period. Concrete, preservative treated wood and PVC tended to have the highest species diversities. A successional study was also carried out. Over a 12-month exposure period epifaunal biodiversity increased on all five materials. After 12 months of exposure, the epifaunal assemblage structure was still significantly different between materials but had become more similar indicating a successional change towards a stable assemblage on all panels. The results indicate that material type and season have a significant effect on epifaunal assemblage structure after short (three-month) periods of submersion but that these effects are reduced with increasing length of exposure. The study concludes that the choice of construction material for an artificial reef will have little effect on the long-term epifaunal community structure, as long as the material is physically stable, non-toxic and offers a high degree of habitat complexity.     

Enhancement of rural domestic sewage treatment performance, and assessment of microbial community diversity and structure using tower vermifiltration

The performance of a novel three-stage vermifiltration (VF) system using the earthworm, Eisenia fetida, for rural domestic wastewater treatment was studied during a 131-day period. The average removal efficiencies of the tower VF planted with Penstemon campanulatus were as follows: chemical oxygen demand, 81.3%; ammonium, 98%; total nitrogen, 60.2%; total phosphorus, 98.4%; total nitrogen, mainly in the form of nitrate. Soils played an important role in removing the organic matter. The three-sectional design with increasing oxygen demand concentration in the effluents, and the distribution of certain oxides in the padding were likely beneficial for ammonium and phosphorus removal, respectively. The microbial community profiles revealed that band patterns varied more or less in various matrices of each stage at different sampling times, while the presence of earthworms intensified the bacterial diversity in soils. Retrieved sequences recovered from the media in VF primarily belonged to unknown bacterium and Bacilli of Firmicutes.     

Case study of complaints on drinking water quality

Several families of Talca city, Chile complained to health authorities for what they attributed to consumption of copper (Cu)-contaminated drinking water. We assessed the situation 6–12 mo after the initiation of complaints by characterizing the symptoms reported, the chemistry of drinking water, and the Cu concentration in stagnant drinking water. After completing a census, 1778 households accepted participation and were categorized as follows: category 1, Cu plumbing for tap water and dwellers reporting health complaints (HC); category 2, Cu plumbing for tap water and dwellers reporting no HC; category 3, plastic plumbing for tap water and dwellers reporting no HC. Questionnaires recorded characteristics of households and symptoms presented by each member of the family in the last 3 mo. The Cu concentration in drinking water was measured in a subsample of 80 homes with Cu pipes. In category 1, participants presented significantly more abdominal pain, diarrhea, and/or vomiting (gastrointestinal [GI] symptoms) in comparison to category 3 and to categories 2 plus 3. The stagnant Cu concentrations measured in drinking water in all houses studied were below the US Environmental Protection Agency guideline value (<1.3 mg Cu/L). In summary, data obtained by interviews suggested that individuals in some areas of Talca city were suffering more GI symptoms potentially related to Cu excess, but measurement of Cu concentration in stagnant tap waters ruled out the association between Cu exposure and GI symptom reports at the time of this study. The dose-response curves for GI symptoms and Cu exposure now available were crucial in the analyses of results.     

Potassium selective chemically modified field effect transistors based on AlGaN/GaN two-dimensional electron gas heterostructures

We investigate the use of the AlGaN/GaN high electron mobility transistor (HEMT) as a novel transducer for the development of ion-selective chemically modified HEMT sensors (ChemHEMTs). For this, polyvinyl chloride (PVC) membrane doped with ion-selective ionophores is deposited onto the area of the gate for the chemical recognition step, while the AlGaN/GaN HEMT is used as the transducer. In particular, the use of a valinocycin doped membrane with thickness of 50 μm generates a sensor with excellent analytical characteristics for the monitoring of K⁺. The K⁺-ChemHEMT has sensitivity of 52.4 mV/pK⁺in the linear range of 10⁻⁵ to 10⁻² M, while the detection limit is in the order of 3.1 × 10⁻⁶ M. Also, the sensor shows selectivity similar to valinomycin-based ISEs, while the signal stability over time and the measurement to measurement reproducibility are very good.     

微塑料对大型溞的急性毒性研究

为了解微塑料对淡水生态环境的影响,选择了大型溞作为受试生物,研究了聚氯乙烯(PVC)对其产生的急性毒性效应与恢复试验.研究设置了7个PVC浓度梯度,范围是0-400 mg/L,等比系数为2,对其进行急性毒性处理,测定96h LC50,并对大型溞心率变化和抗氧化指标进行测定.同时,对其进行清水21d恢复实验.96h LC...     

Relationships between pollutant discharge and water quality in the rivers from “better” to “worse” water quality

The long-term relationship between pollutant discharge and river water quality of biological/biochemical oxygen demand (BOD) in the Yamato-gawa River, Japan, has been found to be similar to perturbation or dynamic equilibrium change of alternative stable states in the ecosystem fields with a linear relationship as a usual condition. Similar relationships have been observed in short-terms for single precipitation events both in the Richmond River, Australia, and in a mountainous watershed in Japan. On the contrary, nutrient concentrations have not changed in a long-term besides nutrient discharge increases in the Richmond River. In this paper, long-term chronological relationships of annual pollutant discharges and water quality in the Brisbane River, Australia, were investigated based on pollutant discharge estimations and water quality monitoring data as a case study in the “better” water quality river. Effects of precipitation variation were taken into account in the pollutant discharge estimations by introducing precipitation variance coefficient (PVC). Total nitrogen (TN) and total phosphorus (TP) concentrations in the river were found to be improved with fluctuations in the lower Brisbane River Catchment during 1975–2012. Long-term dynamic equilibrium alterations of pollutant discharge and water quality were found for TN and TP at the first time in the Brisbane River. The investigated term was found to be divided into two phases, 1975–2001 and 2001–2012 for TN, and 1975–2007 and 2005–2012 for TP. Both pollutant discharges and pollutant concentrations in the river were smaller in Phase 2 than Phase 1. Based on the relationships in the three rivers, a hypothesis on pollutant discharge and water quality from “better” to “worse” river water environment was presented that rapid and/or excess pollutant discharge increases cause perturbation or dynamic equilibrium alterations with the basal relationships as the linear relationships.